1. Field of the Invention
This invention relates to a planetary-gear train for a hybrid-drive vehicle driven by at least one of muscle power and an auxiliary motor.
2. Description of the Prior Art
A hybrid-drive vehicle with a planetary-gear train is taught by Dutch Patent Disclosure NL-A-7,611,405 in which the auxiliary motor drives the sun wheel and muscle power acts on the planetary-gear carrier. Power take-off is accomplished through an outer ring with inner teeth, the crown gear. Such a gear train utilizes a variable transmission ratio. Although planetary-gear trains have been known for years and the use of hybrid-drive vehicles was publicized more than ten years ago, this solution has not prevailed. Studies have shown that there are two essential reasons. In this arrangement, the pedal drive in conjunction with the planetary-gear carrier and the power take-off in conjunction with the hollow wheel with inner teeth, the crown gear, rotate in the same direction and the motor drive of the sun wheel rotates in the opposite direction. The result is that with an increased number of revolutions of the motor, the energy losses due to meshing of the gear train increase. In addition, it is relatively difficult to combine the addition of a transfer case for the muscle power with the known planetary-gear train. Accordingly, the total structure requires a relatively large space.